JPH07232658A - Power steering device - Google Patents

Abstract

PURPOSE:To eliminate the need for using a seam member and not improve durability by a method wherein a valve actuating mechanism is actuated by a movement direction converting means to convert relative rotation between an input shaft and an output shaft into movement in an axial direction of the two shafts. CONSTITUTION:A torsion bar 12 is twisted according to the load of a rack 18 and relative movement displacement occurs between an input shaft 10 and a pinion shaft 14. When a sleeve member 70 is moved to above in an axial direction, a left drain poppet is pressed by a flange 70C against the set load of a drain spring 48 and the through-hole 42A for drain of a spool valve is closed by a conical head 44A. When relative rotation is further increase, a spool valve 42 is moved against the set load of an inlet spring 46. Since the taper surface of a land 42D is separated away from an edge part along with movement thereof, a pressure applied on an accumulator is introduced through an operation chamber 50 to the left actuating oil pressure chamber 22L of a cylinder 22 to exert an assist force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering system having a spool valve type valve actuating mechanism.

[0002]

2. Description of the Related Art Conventionally, a power steering device of this type is known from Japanese Patent Application Laid-Open No. 60-199765.

In this system, a spool valve, which is a valve actuating mechanism for controlling the supply and discharge of hydraulic pressure to and from a cylinder which generates an assisting force, rotates in a housing integrally with a pinion shaft having a pinion that meshes with a rack. It is arranged to be housed in the valve body. Then, a plurality of annular grooves as hydraulic oil passages are formed on the outer periphery of the valve body so as to communicate with a predetermined portion of the valve operating mechanism.

[0004]

However, in such a conventional device, since the valve actuating mechanism is arranged on the valve body which rotates integrally with the pinion shaft in the housing, it is said to be miniaturized. Although it can be evaluated from a viewpoint, in order to prevent the hydraulic oil from leaking from the annular groove serving as the hydraulic oil passage, a seal member had to be mounted between the outer circumference of the valve body and the inner circumference of the housing. .

Since the valve body which rotates integrally with the pinion shaft always rotates during steering, it is easily deteriorated due to wear caused by rotation, which is not preferable from the viewpoint of durability.

An object of the present invention is to provide a power steering device which can improve durability by eliminating the use of such a seal member.

Other objects of the present invention will be apparent from the description of the embodiments described later.

[0008]

In order to achieve the above object, according to one aspect of the present invention, an input shaft to which a steering force is input and an output shaft for driving a steering member are connected by a torsion bar.
In a power steering device having a spool valve type valve operating mechanism that is operated according to a relative rotation amount of the input shaft and the output shaft, the spool valve type valve operating mechanism is configured to rotate the input shaft and the output shaft. Arranged on a supporting fixed member, a motion direction converting means for converting the relative rotation of the input shaft and the output shaft into a motion in the axial direction of the both shafts is provided, and the valve operating mechanism is operated by the motion direction converting means. It is characterized by doing so.

Further, according to another aspect of the present invention, the spool valve type valve actuating mechanism is arranged parallel to the input shaft, and the motion direction converting means is slidable in the axial direction on the input shaft. And an inclined guide portion that is fitted to the
A sleeve member having an axial guide portion, a flange for driving the valve actuating mechanism, a drive pin protruding from the input shaft and engaging with the inclined guide portion, and a drive member fixed to the output shaft. And a guide pin that engages with the axial guide portion.

According to still another aspect of the present invention, the spool valve type valve actuating mechanism is arranged in parallel with the input shaft, and the motion direction converting means slides integrally with the input shaft in the axial direction. A sleeve member and a ring member that are movably fitted, the sleeve member including an inclined guide portion inclined with respect to an axis and a guide portion in the axial direction, and the valve operating mechanism driving lever. A ring member rotatable with respect to the member, a drive pin protruding from the input shaft and engaging with the inclined guide portion, and a guide pin fixed to the output shaft and engaging with the axial guide portion. It is characterized by being

Still another aspect of the present invention is that the spool valve type valve actuating mechanism is arranged in a direction perpendicular to the input shaft, and the motion direction converting means is integrally formed with the input shaft in the axial direction. First and second sleeve members slidably fitted to each other, the first sleeve member having a first inclined guide portion inclined to the axis and a guide portion in the axial direction, and to the axis A second sleeve member, in which a second inclined guide portion that is inclined is formed, and a ring member that includes the lever for driving the valve actuating mechanism and a pin that engages with the second inclined guide portion is fitted, and the input shaft. It is characterized in that it is provided with a drive pin projectingly provided and engaged with the first tilt guide portion, and a guide pin fixedly provided on the output shaft and engaged with the axial direction guide portion.

In a preferred embodiment of the present invention, the fixed member is a housing fixed to a cylinder that slidably supports the steering member.

[0013]

According to the present invention, when the steering force is input to the input shaft, the output shaft connected by the torsion bar rotates and the steering member is driven. At this time, if the load on the steering member is large, the torsion of the torsion bar causes relative rotation between the input shaft and the output shaft. This relative rotation is converted into the axial movement of the input shaft by the movement direction changing means, and the spool valve type valve actuating mechanism arranged on the fixed member is actuated.

Therefore, since the spool valve type valve actuating mechanism is arranged on the fixed member, the conventional seal member is not required.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, 10 is an input shaft connected to a column shaft (not shown), and has a torsion bar 12 inside its hollow. One end of the torsion bar 12 is fixed to the input shaft, and the serration at the other end is engaged with the same serration of the pinion shaft 14 as the output shaft so as not to rotate relative thereto. Pinion shaft 14
The pinion is engaged with a rack 18 formed integrally with a piston rod 16 as a steering member. A piston 20 is fixedly mounted on the piston rod 16, and a cylinder 22 is defined into left and right working hydraulic chambers 22L and 22R, respectively.

In the present embodiment, the cylinder 22 and the gear housing are integrally formed, and the piston rod 16 integrally formed with the rack 18 drives the knuckle arm via a predetermined linkage to perform steering. Done.
Therefore, the cylinder 22 is used herein in the same meaning as the gear housing.

The pinion shaft 14 is rotatably supported on the cylinder 22 by bearings 24 and 26.

Reference numeral 30 denotes a housing fixed to the cylinder (gear housing) 22 as a fixing member. In this embodiment, there are three parts, that is, a bottom part 30A and an intermediate part 30.
B, upper part 30C. A bearing 32 is disposed on the upper portion 30C of the housing to rotatably support the input shaft 10. Further, a spool valve type valve actuating mechanism 40 is arranged in the middle portion 30B of the housing.

The valve actuating mechanism 40 is arranged in a symmetrical relationship so as to control the hydraulic pressures of the left and right actuating hydraulic chambers 22L and 22R. Therefore, although only one side will be described, when it is necessary to distinguish the left side from the right side, “L” is attached to the left and “R” to the right after the reference numeral.

The valve actuating mechanism 40 includes a housing intermediate portion 30.
An inlet spring for urging the spool valve 42, the drain poppet 44, and the spool valve 42, which are slidably disposed in a hole formed in B in parallel with the axes of the input shaft 10 and the output shaft 14, in a closing direction. 46 and a drain spring 48 provided between the spool valve 42 and the drain poppet 44. The spring constant of the inlet spring 46 is set to be larger than that of the drain spring 48.

The spool valve 42 has a drain through hole 42A formed at the center thereof, and a first land 42C having a seal 42B mounted thereon and a second land 42D having a tapered surface formed at the outer periphery thereof. There is.

Further, the drain poppet 44 has a conical head 44A at its tip to close the through hole 42A of the spool valve 42.
Is provided with a flange 44B also serving as a seat of the drain spring 48 in the middle portion, and the drain hole 4 is provided in the flange 44B.
4C is drilled.

Further, the above-mentioned housing intermediate portion 30B.
The holes are expanded at both ends to form working chambers 50. Further, the dimension is set so that the edge portion caused by the diameter expansion comes into contact with the tapered surface of the spool valve 42 described above.

The working chamber 5 is provided in the middle portion 30B of the housing.
Cylinder ports 51L and 51R communicating with 0, and the first land 42C and the second land 42 of the spool valve 42.
Pump port 52 communicating with the space defined between D and
L and 52R are formed.

The discharge side of the pump 62 driven by the motor 60 is connected to the pump ports 52L and 52R through the check valve 64. In this embodiment, the accumulator 66 is arranged in this communication passage, and the pressure operation switch 68 is operated when the accumulated pressure falls below a predetermined pressure to rotate the motor 60.

The structure described above is common to the first and second embodiments (FIGS. 1 and 2) of the present invention.

Next, the structure of the motion direction converting means will be described. In the first embodiment of the present invention, the sleeve member 70 is used.
Is equipped with.

The sleeve member 70 is fitted on the input shaft 10 so as to be slidable in the axial direction, and has a long hole 70A having a predetermined width as an inclined guide portion inclined to the axial line in its middle abdomen.
Are formed. The slot is not limited to the slot, and a slot may be formed on the inner peripheral surface of the slot. Also, the sleeve member 7
Reference numeral 0 has a guide groove or guide slot 70B as an axial guide portion on the lower side thereof, and a disc-shaped flange 70C for driving the valve actuating mechanism formed on the upper portion thereof.

A drive pin 72 formed in the input shaft 10 is engaged with the elongated hole 70A of the sleeve member 70, and a guide pin 74 fixed to the pinion shaft 14 as an output shaft is provided in the guide groove 70B. Engaged.

Thus, the disc-shaped flange 70C described above is used.
Are arranged so as to be held by the rear end portions 44DL and 44DR of the left and right drain poppets 44 of the valve actuating mechanism 40 arranged in line symmetry.

In the first embodiment of the present invention having such a structure, no steering force is applied, that is, when the vehicle is traveling straight in neutral, the state shown in FIG. 1 is reached, and the pressure accumulated in the accumulator 66 is It is retained by the check valve 64 and the spool valve 42 in the closed position. At this time, the pump 62 is stopped. The spool valve 42 does not move because the inlet spring 46 has a larger spring constant than the drain spring 48 and the pressure receiving surfaces of the pressure acting surfaces of the lands 42C and 42D are set to be equal.

When the steering wheel is steered and the steering force is input to the input shaft 10, the pinion shaft 14 rotates via the torsion bar 12 and the piston rod 16 on which the rack 18 is formed moves in either the left or right direction. Wheels are steered.

At this time, the torsion bar 12 is twisted in accordance with the load of the rack 18, and a relative rotational displacement is generated between the input shaft 10 and the pinion shaft 14 according to the amount of twist. Therefore, the sleeve member 70 in which the relative rotation with the pinion shaft 14 is prevented by the engagement between the guide pin 74 and the guide groove 70B is input by the engagement between the drive pin 72 of the input shaft 10 and the inclined elongated hole 70A. The shaft 10 moves in either axial direction with the relative rotation of the shaft 10. For example, when the sleeve member 70 is moved upward in the axial direction, the flange 70C causes the left drain poppet 44L to move to the drain spring 4 and the left drain poppet 44L.
8 against the set load, the conical head 44A closes the drain through hole 42A of the spool valve.

When the relative rotation further increases, the spool valve 42 is moved against the set load of the inlet spring 46. Land 42 along with this movement
Since the taper surface of D separates from the edge portion, the pressure accumulated in the accumulator passes through the working chamber 50 and is introduced into the left-side working hydraulic chamber 22L of the cylinder 22 to give an assist force.

At this time, the working oil in the right working hydraulic chamber 22R escapes into the housing 30 from the working chamber 50R, the through hole 42AR of the spool valve and the through hole 44C of the drain poppet.
It is drained to the drain tank D through the drain hole 30D.

Next, a second embodiment of the present invention will be described. This embodiment is different from the previous embodiment in the part of the movement direction converting means as described above, and the sleeve member 70.
The structure of the portion corresponding to the flange 70C integrally formed with the is different.

That is, the sleeve member 170 of the second embodiment has the same structure as the sleeve member 70 except that the flange 170C has a smaller diameter than the flange 70C of the previous embodiment, and has an inclined elongated hole 170A and an axial guide groove. 170B
Is equipped with.

Then, the flange 1 of the sleeve member 170
A ring member 174 is rotatably provided via a thrust bearing 172 on the 70C.
Is held by a collar 176 so as to move integrally with the sleeve member 170 in the axial direction.

Further, the ring member 174 is provided with a lever 174A for driving the valve actuating mechanism 40, and the lever 174A is located between the left and right drain poppets 44L, 44R at the neutral position as in the previous embodiment. It is located in abutment. It is the same as in the previous embodiment that the drive pin 72 projecting from the input shaft 10 engages with the inclined elongated hole 170A and the guide pin 74 engages with the guide groove 170B.

However, when there is a relative displacement between the input shaft 10 and the pinion shaft 14 which is the output shaft, the sleeve member 170 moves in the axial direction together with the ring member 174 as in the previous embodiment, and the valve operating mechanism. 40 is driven. However, while the ring member 174 rotates together with the pinion shaft 14 of the sleeve member 170, the ring bearing 174 remains in the same rotational position by the action of the thrust bearing 172.

Therefore, in this embodiment, since the ring member 174 which is rotatable with respect to the input shaft 10 is provided,
Since the lever 174A for driving the valve actuation mechanism can be stopped at a fixed position, the housing 30 can be made smaller.

Next, a third embodiment of the present invention will be described with reference to FIG.
It will be described with reference to FIGS.

The major difference between this embodiment and the previous embodiment is that
This is because the valve actuating mechanisms 40 arranged symmetrically are arranged in the direction perpendicular to the axis of the input shaft 10, and the movement direction converting means is changed in accordance with the change in the arrangement.

That is, the valve actuating mechanism 1 according to this embodiment.
The basic operation of 40 is similar to that of the previous embodiment, but some changes are made in the structure.

First, referring to FIG. 4, the valve actuating mechanism 1 of the present example.
Reference numeral 40 includes left and right valve bodies 141, and the valve bodies 141 are fixed to the housing 130 in a direction perpendicular to the axis of the input shaft 10. A spool valve 142 and a drain poppet 144 are slidably arranged in a hole formed in the valve body 141. The spool valve 142 includes an inlet spring 14 held by a plug 147 screwed to the valve body 141.
As in the previous embodiment, the taper surface is biased by 6 and is held in the closed position where the tapered surface abuts the edge portion.

In this embodiment, a drain port 149 is formed in the valve body 141 instead of the drain hole 44C of the drain poppet 44 in the previous embodiment. Since the other parts are the same as those in the previous embodiment, the same functional parts are indicated by the reference numerals used in the previous embodiment plus 100, and the duplicated explanation is omitted.

Next, the housing 130 is formed in a substantially cylindrical shape and is fixed to the cylinder (gear housing) 22.

The motion direction changing means in this embodiment includes first and second sleeve members 270 and 370 which are fitted on the input shaft 10 so as to be slidable integrally in the axial direction. The first sleeve member 270 has a first inclined elongated hole 270A similar to the sleeve members 70 and 170 of the previous embodiment, an axial guide groove 270B, and a small diameter flange 270. The second sleeve member 370 has the first inclined elongated hole 270.
It has a second inclined elongated hole 370A and a flange 370C that are inclined in the same direction as A. And the first and second
The flange members of the sleeve members 270 and 370 are opposed to each other, as shown in FIG. 5, and are interposed by the thrust bearing 272 and are connected by the connecting ring 274. The connecting ring 274 has an L-shaped cross section,
The short piece portion and the flange 37 of the second sleeve member 370.
After the thrust bearing 276 is interposed between the first sleeve member 270 and the flange 2 of the first sleeve member 270.
By screwing to 70C, both sleeve members are axially connected while allowing relative rotation.

Further, a ring member 372 is fitted on the outer circumference of the second sleeve member 370, and the ring member 372 has a lever 372A protruding outward and a pin 372B protruding inward. ing. Pin 372B is second
Second inclined elongated hole 370 formed in the sleeve member 370.
The lever 372A extends into the through hole 130A of the housing 130, and the adapters 374L and 374R are interposed between the oppositely arranged drain poppets 144L and 144R of the valve actuating mechanism 140. It is located in. The through hole 130A allows only the rotational movement of the lever 372A and restricts the movement in the axial direction.

In the third embodiment of the present invention having the above construction, the input shaft 10 and the pinion shaft 1 as the output shaft 1
When there is relative displacement in the rotational direction between the first slide member 270 and the second slide member 370, the drive pin 72 projecting from the input shaft 10 and the first inclined elongated hole 270A are engaged with each other. Both move axially. When the second slide member 370 moves in the axial direction, the pin 372B moves to the second position.
Member 372 engaged with the inclined long hole 370A of
Rotates due to the cam action, and its lever 372A moves the drain poppet 144 via the adapter 374.

As described in the previous embodiment, however, the drain poppet 144 and thus the spool valve 142 are moved so that the pressure oil is supplied to the predetermined working hydraulic chamber, and the assist force is generated.

In the above-mentioned embodiment, it differs depending on whether the direction of the valve actuating mechanism (the axial direction of the spool valves symmetrically arranged) is arranged parallel to the input shaft or at right angles. This difference is effective because it is possible to select a layout-friendly one in the vehicle.

Further, in the above-described embodiment, even if the rack (in this example, the same as the piston rod 16) is eccentric when the vehicle bounces, as long as the relative angular displacement between the output shaft and the input shaft does not occur. Since the valve actuating mechanism does not operate, there is also an effect that steering rigidity is improved and straight running performance of the vehicle is improved without generating an assisting force.

[0055]

As is apparent from the above description, according to the present invention, since the spool valve type valve actuating mechanism is arranged on the fixed member, it is possible to eliminate the need for a seal member which causes a durability problem. You can

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a sectional view showing a third embodiment of the present invention.

4 is a cross-sectional view taken along the line AA of FIG.

5 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

 10 Input Shaft 12 Torsion Bar 14 Pinion Shaft (Output Shaft) 30 Housing 40,140 Valve Actuating Mechanism 42,142 Spool Valve 44,144 Drain Poppet 70,170,270,370 Sleeve Member 70A, 170A, 270A, 370A Inclined Long Hole 70B, 170B, 270B Guide groove 70C, 170C Flange 72 Drive pin 74 Guide pin 174,372 Ring member 174A, 372A Lever

Claims (5)

[Claims] 1. A spool valve type which is constructed by connecting an input shaft to which a steering force is input and an output shaft for driving a steering member with a torsion bar, and which is operated according to a relative rotation amount between the input shaft and the output shaft. In a power steering device having a valve actuating mechanism, the spool valve type valve actuating mechanism is disposed on a fixed member that rotatably supports the input shaft and the output shaft, and the relative rotation between the input shaft and the output shaft is controlled by the both members. A power steering device comprising: a motion direction converting means for converting the motion of the shaft into an axial direction, and the valve operating mechanism is operated by the motion direction converting means. 2. The spool valve type valve actuating mechanism is arranged in parallel with the input shaft, and the motion direction converting means is slidably fitted on the input shaft in the axial direction and inclined with respect to the axial line. A sleeve member having an inclined guide portion, an axial guide portion, and a flange for driving the valve operating mechanism, a drive pin protruding from the input shaft and engaging with the inclined guide portion, and the output shaft The power steering device according to claim 1, further comprising a guide pin that is fixedly mounted on the guide pin and that engages with the axial guide portion. 3. The spool valve type valve actuating mechanism is arranged in parallel with the input shaft, and the movement direction converting means is a sleeve member fitted integrally with the input shaft so as to be slidable in the axial direction. And a ring member, which includes a sleeve member having an inclined guide portion inclined to the axis and a guide portion in the axial direction, and a ring member including the valve actuating mechanism driving lever and rotatable with respect to the sleeve member. And a drive pin protruding from the input shaft and engaging with the inclined guide portion, and a guide pin fixed to the output shaft and engaging with the axial guide portion. The power steering device according to. 4. The spool valve type valve actuating mechanism is disposed in a direction perpendicular to the input shaft, and the motion direction converting means is mounted on the input shaft so as to be slidable integrally in the axial direction. A first and a second sleeve member, in which a first inclined guide portion inclined to the axis and a guide portion in the axial direction are formed, and a second inclined guide portion inclined to the axis is formed. A second sleeve member fitted with a ring member having the valve operating mechanism driving lever and a pin that engages with the second tilt guide portion; and the first tilt guide portion projectingly provided on the input shaft. 2. The power steering apparatus according to claim 1, further comprising: a drive pin that engages with the drive shaft; and a guide pin that is fixed to the output shaft and that engages with the axial guide portion. 5. The power steering apparatus according to claim 1, wherein the fixed member is a housing fixed to a cylinder that slidably supports the steering member.